Frequency channel diversity for real-time locating systems, methods, and computer program products

ABSTRACT

Provided are architectures, systems, methods, and computer program products for real-time object locating and position determination using frequency channel diversity for transmitting and receiving position determination signals including bursts of location signals. Channelized frequency diversity of a short burst of small location signals that “hop” across multiple frequency channels is used to collectively produce a quasi-wideband position determination signal. Object tags operating with frequency channel diversity for transmitting location signals of position determination signals require low power consumption, but can still efficiently provide adequate position determination signals for reliable position determination.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent arises from a continuation of U.S. patent application Ser.No. 14/323,534, filed Jul. 3, 2014, now U.S. Pat. No. 9,684,054, whichis a continuation of U.S. patent application Ser. No. 12/836,164, filedJul. 14, 2010, now U.S. Pat. No. 8,786,495, which are herebyincorporated herein in their entireties by reference.

FIELD OF THE INVENTION

Embodiments of the present invention relate generally to wireless datatransmissions and, more particularly, relate to wireless datatransmissions using frequency channel diversity for real-time locatingsystems, methods, and computer program products.

BACKGROUND

Position determination is increasingly important for both commercial andpersonal applications. Real-time locating systems (RTLS) are used andrelied upon for tracking objects, such as determining the location of anobject within storage, shipping, retail, and/or manufacturingsituations. Wireless transmitters or tags are commonly attached to orembedded in objects to provide wireless position determination signalsto one or more wireless receivers or readers. Information about and/orfrom the wireless position determination signals can be used todetermine a location of the object.

Many traditional and more recently developed real-time locating systemsare typically challenged by similar problems, including available power,signal strength, interference, and available bandwidth. Generally,increased reliability of the wireless position determination signal froman object tag to a receiver will result in increased accuracy in theinformation that is available to determine the position of the object.One way to increase the reliability of the wireless positiondetermination signal is to increase the bandwidth of the signal.However, increasing the bandwidth of the signal requires more energy(e.g., battery power), requires that the increased bandwidth beavailable for use, and typically causes increased interference problems.Many real-time locating systems are also challenged by infrastructurecosts. Improving position determination typically has a correspondingcost increase, such as to increase the number of receivers or to usemore robust object tags.

Numerous technologies are available to implement different real-timelocating systems corresponding to the relevant application of thetechnology and desired results. And significant improvements have beenmade to various technologies that can be used for real-time locatingsystems. However, even in view of available technologies andimprovements, it is still desirable to improve upon these existingtechniques to address remaining limitations of the various technologiesand to provide alternate technologies that may be preferred in certaininstances. For example, there is a need in the art for improvedarchitectures, systems, methods, and computer program products forreal-time object locating and position determination that decreaseand/or avoid problems of existing technologies. Similarly, for example,there is a need in the art for alternate technologies for real-timeobject locating and position determination that may be preferred incertain instances.

SUMMARY

In light of the foregoing background, embodiments of the presentinvention provide architectures, systems, methods, and computer programproducts for real-time object locating and position determination usingfrequency channel diversity for transmitting and receiving positiondetermination signals in the form of location signal bursts, i.e., eachposition determination signal is a burst of wireless location signals.Embodiments of the present invention may advantageously use object tagsthat require low power consumption, but can still efficiently provideadequate position determination signals for reliable positiondetermination. For example, by using frequency channel diversity narrowbandwidth location signal bursts, less power may be used than usingultrawideband (UWB) transmissions. Similarly, for example, by usingfrequency channel diversity frequency hopping for bursts of narrowbandwidth location signals, position determination accuracy improvesover what is possible with a single narrow channel signal. Embodimentsof the present invention also may advantageously use off-the-shelfhardware and existing infrastructures, which may be helpful to decreasecosts and increase opportunities to employ applications of embodimentsof the present invention. Additional advantages of using frequencychannel diversity for position determination are described furtherherein.

Embodiments of methods of the present invention are provided thatdetermine the position of an object based upon data for a plurality ofseparate wireless location signals transmitted over multiple frequencychannels by the object and received by a plurality of receivers andtransmitted from the plurality of receivers to a computer to perform theposition determination. The multiple frequency channels of anotherembodiment may be selected from a predetermined set of availablefrequency channels. The plurality of separate wireless location signalsof a further embodiment may be transmitted over a consecutive series offrequency channels. Position determination may be achieved in yet afurther embodiment by correlating data from at least two of theplurality of receivers for at least one of the separate wirelesslocation signals transmitted over one of the frequency channels.Alternatively, or in addition, position determination may be achieved inyet a further embodiment by correlating data from one of the pluralityof receivers for one of the separate wireless location signalstransmitted over one of the frequency channels and data from another ofthe plurality of receivers for another of the separate wireless locationsignals transmitted over another of the frequency channels. Data may bediscarded in yet a further embodiment if not desired for determining theposition of the object, such as if the data for a wireless locationsignal is not transmitted from at least three of the plurality ofreceivers. For example, in some embodiments, data may be discarded ifdetermined to be outside of an acceptable range of values, and theacceptable range of values may be determined based upon the data fromthe plurality of receivers. In yet a further embodiment, a data loadpartition between two or more of the separate wireless location signalsmay be compiled to facilitate or supplement the position determination.It should be expressly contemplated and understood that one or more ofthe above functions of the several described embodiments may becombined, and will typically be combined, when not inherently precludedas exclusive alternate functions, to achieve various embodiments ofcombinations of functions of the present invention. In this respect, itshould also be expressly contemplated and understood that redundancyand/or overdetermination may be preferred in an embodiment of thepresent invention to improve the accuracy of the position determinationand are, therefore, not inherently precluded as exclusive alternatefunctions, but instead are typically additive functions.

Embodiments of wireless tags of the present invention are provided thatinclude a controller and a wireless transmitter. The controller may beconfigured to generate a plurality of location signals for collectiveindividual transmission over multiple frequency channels of apredetermined set of available frequency channels. The wirelesstransmitter may be configured to transmit the location signals of theposition determination signal over the multiple frequency channels uponinstruction by the controller to cause the transmission of the locationsignals over at least two of the predetermined set of availablefrequency channels. In another embodiment, the controller may beconfigured to determine if one of the predetermined set of availablefrequency channels is in use and, when that frequency channel is in use,to at least temporarily exclude that frequency channel from the multiplefrequency channels used to transmit the plurality of location signals.In yet another embodiment, the controller may be configured to partitiona data load between two or more of the plurality of location signalsand, optionally, the data load may be evenly distributed amongst thepartitions. Further, the data load may be partitioned between fewer ofthe plurality of location signals in the number of frequency channels ofthe predetermined set of available frequency channels. In yet anotherembodiment, the controller may be configured to cause the wirelesstransmitter to transmit the location signals over at least twoconsecutive frequency channels of the predetermined set of availablefrequency channels. In yet another embodiment, the predetermined set ofavailable frequency channels may comprise sixteen channels. In addition,or alternatively, in yet another embodiment, the frequency channels ofthe predetermined set of available frequency channels may be 5 MHzchannels. It should be expressly contemplated and understood that one ormore of the above elements and functions of the several describedembodiments may be combined, and will typically be combined, when notinherently precluded as exclusive alternate elements or functions, toachieve various embodiments of combinations of elements and/or functionsof the present invention. In this respect, it should also be expresslycontemplated and understood that redundancy and/or overdetermination maybe preferred in an embodiment of the present invention to improve theaccuracy of the position determination and are, therefore, notinherently precluded as exclusive alternate elements and/or functions,but instead are typically additive elements and/or functions.

Embodiments of receivers of the present invention are provided thatinclude a wireless receiver, a controller, and a transmitter. Thewireless receiver may be configured to receive a plurality of locationsignals transmitted over multiple frequency channels, such as multiplefrequency channels of a predetermined set of available frequencychannels. The controller may be configured to determine location data ofeach of the plurality of location signals. The transmitter may beconfigured to transmit the location data of the plurality of locationsignals to a central computer. In another embodiment, the controller maybe configured to discard location signals of the plurality of locationsignals that are determined to be outside of an acceptable range ofvalues, such as determined by the controller based upon the plurality oflocation signals. In yet another embodiment, the controller may beconfigured to compile a data load partitioned between the data of two ormore of the plurality of location signals, and the transmitter maytransmit the data load. In yet another embodiment, the receiver maycomprise a timer configured to measure an arrival time of each of theplurality of location signals, the controller may be configured toassociate each of the plurality of location signals with an arrival timeof each of the plurality of location signals, thereby defining thelocation data, and the transmitter may be configured to transmit thearrival time with each of the plurality of location signals to thecentral computer. In yet another embodiment, the receiver may comprise atimer configured to measure an arrival time of each of the plurality oflocation signals, the controller may be configured to determine the timedifferences of arrival between each of the plurality of locationsignals, thereby defining the location data, and the transmitter may beconfigured to transmit the time of arrival of at least one of theplurality of location signals and the time differences of arrivalbetween each of the plurality of location signals to the centralcomputer. It should be expressly contemplated and understood that one ormore of the above elements and functions of the several describedembodiments may be combined, and will typically be combined, when notinherently precluded as exclusive alternate elements or functions, toachieve various embodiments of combinations of elements and/or functionsof the present invention. In this respect, it should also be expresslycontemplated and understood that redundancy and/or overdetermination maybe preferred in an embodiment of the present invention to improve theaccuracy of the position determination and are, therefore, notinherently precluded as exclusive alternate elements and/or functions,but instead are typically additive elements and/or functions.

The characteristics referred to above, as well as additional details, ofthe present invention are described below. Similarly, corresponding andadditional embodiments of frequency channel diversity real-time locatingarchitectures and related systems, methods, and computer programproducts of the present invention for position determination are alsodescribed below, including, for example, computer program productscomprising a non-transitory computer-usable storage medium havingcontrol logic stored therein for effectuating position determination bya computer.

BRIEF DESCRIPTION OF THE DRAWING(S)

Having thus described embodiments of the invention in general terms,reference will now be made to the accompanying drawings, which are notnecessarily drawn to scale, and wherein:

FIG. 1 is a schematic block diagram of a plurality of participantentities effectuating position determination based upon frequencychannel diversity according to at least one embodiment of the presentinvention;

FIG. 2 is a partial diagram representative of a burst of frequencychannel diversity location signals according to at least one embodimentof the present invention;

FIG. 3 is another partial diagram representative of a burst of frequencychannel diversity location signals according to at least one embodimentof the present invention;

FIG. 4. is a functional block diagram of frequency channel diversitylocation position determination according to at least one embodiment ofthe present invention;

FIG. 5 is a block diagram of a wireless tag according to at least oneembodiment of the present invention;

FIG. 6A is a block diagram of a single channel receiver according to atleast one embodiment of the present invention;

FIG. 6B is a block diagram of a multiple channel receiver according toat least one embodiment of the present invention;

FIG. 6C is a block diagram of a wideband receiver according to at leastone embodiment of the present invention;

FIG. 7 is a block diagram of a computer that may be used to facilitateposition determination based upon frequency channel diversity accordingto at least one embodiment of the present invention;

FIG. 8 is a block diagram representative of a position determinationsignal according to at least one embodiment of the present invention;

FIG. 9 is a block diagram representative of two position determinationsignals according to at least one embodiment of the present invention;and

FIG. 10 is a block diagram representative of a position determinationsignal according to at least one embodiment of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention will now be described more fullyhereinafter with reference to the accompanying drawings, in which some,but not all embodiments of the invention are shown. Indeed, embodimentsof the present invention may be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein;rather, these embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Like reference numbers refer tolike elements throughout. As used herein, the terms “data,” “content,”“information,” and similar terms may be used interchangeably to refer todata capable of being transmitted, received, operated on, and/or storedin accordance with an embodiment of the present invention. Moreover, theterm “exemplary,” as used herein, is not provided to convey anyqualitative assessment, but instead to merely convey an illustration ofan example.

While the present invention is described below in detail with referenceto several exemplary embodiments, it will be appreciated from thefollowing description that many types of objects and various practicalapplications of real-time locating position determination may be usedwith and benefit from embodiments of the present invention, such asdetermining the location of products in storage, vehicles in transit,packages in shipment, inventory in a retail store, parts inmanufacturing plants, animals on a farm or ranch, cars in a parking lotor garage, a cell phone or remote control in a home, patients orequipment in a hospital, and movable and/or portable assets in abusiness office (e.g., video projectors, laptops, printers, etc.). Ingeneral, any type of physical object for which position determinationmay be beneficial may employ embodiments of the present invention.Embodiments of the present invention are not limited to particularobjects, applications, or environments. Moreover, embodiments of thepresent invention are scalable in a number of ways, such as based upondesired distance transmissions and accuracy of position data.

Embodiments of the present invention provide architectures, systems,methods, and computer program products for real-time object locating andposition determination using frequency channel diversity fortransmitting and receiving position determination signals in the form oflocation signal bursts, i.e., each position determination signal is aburst of wireless location signals. As used herein, frequency channeldiversity refers to the use of multiple frequency channels to transmitseparate wireless signals (i.e., channelization of wireless signals), aswell as associated concepts of frequency hopping. For example, wirelessposition determination signals may be channelized as separate locationsignals in multiple narrow frequency bands and collectively butindividually transmitted in a burst across a broader frequency band,i.e., a position determination signal may be a burst of frequencychannel diversity location signals. Frequency channel diversity ofembodiments of the present invention is described below in furtherdetail.

By using frequency channel diversity, embodiments of the presentinvention may use object tags that require low power consumption, butcan still efficiently provide adequate location signals for reliableposition determination. For example, by using frequency channeldiversity narrow bandwidth signals, less power may be used than usingultrawideband (UWB) transmissions. For example, a IEEE 802.15.4a objecttag can operate effectively in a beacon or transmitting mode withfrequency channel diversity for an embodiment of the present inventionover sixteen 5 MHz channels in the 2.4 GHz frequency band with a 250kbps data rate and 15.36 ms pulse spacing with a 1 mW wireless poweroutput.

By using frequency channel diversity narrow bandwidth channelizedlocation signals in forms of frequency hopping, position determinationaccuracy improves for embodiments of the present invention over what ispossible with a single narrow channel signal. The use of multiplefrequency channels achieves diversity of measured data for positiondetermination. Generally, as the diversity of the measured dataincreases, the accuracy of the position determination also increases.Thus, by separately channelizing multiple location signals in narrowfrequency bands across a broader frequency band, embodiments of thepresent invention are able to create a pseudo-ultrawideband (orpseudo-wideband) position determination signal and achieve quality andaccuracy of position data using a low power ultrawideband (UWB) signal.Moreover, embodiments of the present invention employ two forms ofdiversity, frequency and time, both of which may improve accuracy ofposition determination.

Embodiments of the present invention may use multiple narrow frequencybands for channels within one or more broader frequency bands. Thenarrow frequency bands of channels may all be in a single broaderfrequency band, such as the ISM 2.4 GHz frequency band. Alternatively,narrow frequency bands of channels may be within multiple frequencybands, such as from an ultra high frequency (UHF, 300 MHz to 3 GHz) bandand also from the super high frequency (SHF) 5.8 GHz band. For example,an embodiment of the present invention could use multiple 900 MHzchannels and multiple 2.4 GHz channels. Another exemplary embodiment ofthe present invention could use the three separate 2.4 GHz 802.11b/g/hchannels and the eight 5 GHz 802.11a channels as a predetermined set ofavailable frequency channels. A further exemplary embodiment of thepresent invention could combine a 6 GHz ultrawideband pulse beacon witha 2.4 GHz ISO 24730 direct-sequence spread spectrum (DSSS) beacon, whereUWB is advantageous for location accuracy, such as where line-of-sightis available, and where ISO 24730 provides better coverage, such as incluttered environments and over long ranges. Frequency bands may beassigned by regulatory bodies and/or standards organizations, such asdepending upon a country in which an embodiment of the present inventionis used. Further, frequency bands may be selected for optimum use withfrequency hopping techniques applied by embodiments of the presentinvention and specific applications of embodiments of the presentinvention, such as to avoid frequency bands with known interference in aparticular operating environment.

Similar to existing real-time location systems, embodiments of thepresent invention may use various forms of data and correspondingalgorithms to determine the position of an object, such as angle ofarrival (AoA), line of sight (LoS), time of arrival (ToA), timedifference of arrival (TDoA) or differential time of arrival (DToA),perceived channel power indicator (RCPI), received signal strengthindication (RSSI), time of flight (ToF), and combinations thereof. Timeof arrival (ToA), time difference of arrival (TDoA), and received signalstrength indication (RSSI) may be used most commonly. In addition,embodiments of the present invention may be combined with other forms ofdiversity to further enhance or improve accuracy of positiondetermination. For example, embodiments of the present invention may becombined with multiple receiving antenna spatial diversity or tag radiofrequency radiation polarity diversity.

Embodiments of the present invention may use narrow bandwidthchannel-type wireless transmitters and receivers, or combinedtransmitters and receivers (i.e., transceivers (XMTR) or transponders(XPDR)). Such devices typically have lower costs and power consumptionthan wideband and ultrawideband (UWB) counterparts. Embodiments of thepresent invention also may advantageously use off-the-shelf hardware andexisting infrastructures, such as a IEEE 802.15.4a application-specificintegrated circuit (ASIC) tag described above, which may be particularlyhelpful to decrease costs. In addition to IEEE 802.15.4a products, othercommercially available products may also be available, such as alternateASIC or FPGA products, and such as products designated to operate inaccordance with the ZigBee™ specifications of the ZigBee Alliance of SanRamon, Calif.

In addition to taking advantage of affordable transceivers available inmultiple bands, embodiments of the present invention may also takeadvantage of compatible infrastructures. For example, smart power metersand power grid management provide opportunities for combining wirelessinfrastructure for alternative applications to also be used for positiondetermination. In one particular example, which may be characterized aspart of a local power grid management, LED lights for residential and/orcommercial applications may be equipped with transceivers operating inaccordance with IEEE 802.15.4a, ZigBee, or a like specification. Suchproducts are being developed by Philips Electronics North America Corp.of Andover, Mass., and Somerset, N.J., which is a subsidiary ofKoninklijke Philips Electronics N.V. of Amsterdam, the Netherlands. Thetransceivers of LED lights may be used to control the lighting of theLED lights, such as for turning on and off or dimming the LED lights. Insuch a manner, each LED light may be wirelessly controlled, for example,using a mesh network architecture to communicate with and between theLED lights. In an exemplary application of an embodiment of the presentinvention, one or more LED lights with a transceiver may be used as afrequency channel diversity receiver to determine the position of anobject. For example, LED light transceivers in a home may be used tolocate a remote control, such as a cable, satellite, or TV remotecontrol lost between the couch cushions, or to locate a pet, such as thecollar on a cat hiding under a bed. Further, a mesh network architecturemay be advantageous to provide redundancy and/or overdetermination oflocation data, although any one or more receiver configurations andcommunication architectures may be used with embodiments of the presentinvention. More generally, hardware and networking infrastructureestablished for other applications, such as LED light transceivers ormesh network communications, may also be used as location infrastructureof embodiments of the present invention.

FIG. 1 is a schematic block diagram of a plurality of participantentities effectuating position determination based upon frequencychannel diversity according to at least one embodiment of the presentinvention. A single asset or object tag 110 is illustrated relative tomultiple receivers 1, 2, 3, . . . n 101, 102, 103, 104. For example,object tag 110 may be located proximate to and in line-of-sight withreceivers 1 through n 101, 102, 103, 104 and may cooperate to provideposition determination of the object tag 110 relative to receivers 1through n 101, 102, 103, 104, at least one of which may have a knownposition relative to an operating environment or on a larger physicaland/or geographic scale and, thus, by extrapolation, the position ofobject tag at 110 may also be determined relative to the operatingenvironment or on the larger physical and/or geographic scale. Theobject tag 110 will at least include a wireless transmitter forcollectively but individually transmitting a burst of location signalsover multiple frequency channels. Further details of embodiments ofobject tags of the present invention are provided with reference to FIG.5. The receivers 1 through n 101, 102, 103, 104 will similarly at leastinclude a wireless receiver for collectively receiving a burst oflocation signals over multiple frequency channels. Further details ofembodiments of receivers of the present invention are provided withreference to FIG. 6.

In operation, and with reference to FIG. 4, object tag 110 will generatea plurality of separate wireless location signals, as identified inblock 404. Each location signal can provide the same basic informationbecause the location signals are used for position determination, notcommunication. When channelized signals have traditionally been used,partitions of a single signal carry different data loads over multiplechannels to create a single signal transmission, such as forcommunication whereby signal partitions carry relatively large anddifferent data loads to transmit signal to accomplish the communication,i.e., channelizing different information on each channel, typicallytransmitted simultaneously and/or transmitted simultaneously with othersignal transmissions from other “speakers” on the communication network.By comparison, when embodiments of the present invention operate forposition determination, separate location signals do not need to carrylarge or different data loads. Rather, identical or similar smalllocation signals are repeatedly sent over a short period of time on aplurality of frequency channels, thereby providing the ability to obtaina more accurate position determination of the tag and/or objecttransmitting the location signals. Embodiments of the present inventionuse channelized frequency diversity of a short burst of small locationsignals that “hop” across multiple frequency channels to collectivelyproduce a quasi-wideband position determination signal that can moreaccurately measure time and, therefore, more accurately locate thetransmitting tag and/or object than traditionally possible using asingle position determination signal in a narrow frequency band andusing lower power consumption than traditionally possible using awideband or ultrawideband (UWB) position determination signal.

Although each location signal of a position determination signal willtypically provide the same basic information used for positiondetermination, location signals of a position determination signal ofembodiments of the present invention may differ in some respects. Forexample, location signals of a position determination signal may differdue to network overhead, differences in data load, and acceptabletruncations of data, such as only transmitting part of a tag ID todecrease the overall signal load and necessary network throughput. Morespecifically, each location signal typically will include information toidentify the specific tag transmitting the location signals of aposition determination signal. This may be an identification (ID or UID)number for the tag, like a license plate number (LPN). This informationmay be in an ID field for the location signals. In addition, one or morelocation signals of a position determination signal may includeadditional data, referred to herein as a data load. A data load, ifincluded, may be in a data field for the location signals.

The transmission and frequency hopping of the plurality of locationsignals over multiple frequency bands, as identified in block 410, mayoccur according to any one or more different sequential, algorithmic,pseudo-random, or random ways. As a general matter, the hardware and/orcontroller of an object tag will operate over multiple frequencychannels. Further, the hardware and/or controller of an object tag mayalso define a predetermined set of available frequency channels that maybe used. For example, as described above, if an object tag includes aIEEE 802.15.4a transceiver, the object tag may operate over sixteen 5MHz channels in the 2.4 GHz frequency band with a 250 kbps data rate and15.36 ms pulse spacing with a 1 mW wireless power output. This hardwareconfiguration may define the predetermined set of available frequencychannels. Alternately, if an application of an embodiment of presentinvention uses an object tag with this hardware configuration butexisting operations already use one or more of the sixteen 16 frequencychannels, the hardware and/or controller may be further configured todefine a predetermined set of available frequency channels that are theremaining available subset of the sixteen 16 frequency channels that maybe used by the object tag.

FIGS. 2 and 3 are partial diagrams representative of frequency channeldiversity location signals according to embodiments of the presentinvention. In the exemplary frequency diagram of FIG. 2, frequencyhopping ideally occurs sequentially, such as in a numerical order,across a consecutive series of channels A, B, C, D, . . . N. Theexemplary frequency diagram of FIG. 3, illustrates several possiblefrequency hopping algorithms. For example, the frequency hopping mayalso ideally occur sequentially across a consecutive series of channelsA, B, C, D, . . . N, but, such as due to high use or other frequentinterference, certain channels may be skipped or omitted if determinedto be in use or unreliable resulting in a sequential non-consecutiveseries of channels A, D, E, G, . . . N. Alternatively, the frequencyhopping may be algorithmic or pseudo-random and resulting in asequential transmission across a non-consecutive series of channels A,D, E, G, . . . N. Alternatively, the frequency hopping may result in asequential transmission across a non-consecutive series of channels G,H, F, E, D (not illustrated) or a a non-sequential transmission across anon-consecutive series of channels A, G, E, D, F, C, . . . N (notillustrated). The described frequency hopping series of channels areonly exemplary, and any frequency hopping of a position determinationsignal comprising a burst of a plurality of location signals overmultiple frequency bands, as identified in block 410, may be used for anembodiment of the present invention.

A position determination signal comprising a burst of a plurality oflocation signals transmitted over multiple frequency channels inaccordance with an embodiment of the present invention is preferablyshort enough in time duration to represent a near-fixed (point) positionof the object being tracked. For example, an object tag using a singleIEEE 802.15.4a ASIC transceiver may transmit a frequency hopping burstof location signals over sixteen frequency channels in only 245.76milliseconds or 15.36 ms pulse spacing per sixteen channels. In anotherexample, an object tag using a single IEEE 802.15.4a ASIC transceivermay transmit a frequency hopping burst of location signals over sixteenfrequency channels in only 230.4 milliseconds or 14.4 ms pulse spacingper sixteen channels. Embodiments of the present invention may use anylength for diverse multiple frequency channel bursts. Ideally, all ofthe location signals for a position determination signal burst will betransmitted on the involved multiple frequency channels at the same ornear-same physical location. In this way, it can be said that an objecttag may “blink” to transmit a position determination signal comprising aburst of location signals so that multiple location solutions can beobtained by receivers, one location solution for each channel. Forpotentially faster moving objects, shorter burst time durations arepreferred. For anticipated slower moving objects, longer burst timedurations may be possible. For example, if an object tag is anticipatedto be resting at a fixed location, a frequency hopping burst of locationsignals may be of any reasonable length duration because the tag is notexpected to be moving. A more robust tag according to an embodiment ofthe present invention may include multiple transmitters tosimultaneously frequency hop subsets of multiple frequency channels todecrease a total burst duration, such as to transmit a positiondetermination signal with location signals over sixteen channels in foursubsets of four channels in one fourth the total time for a singletransmitter to transmit 16 locations signals over sixteen channels. Asmart tag according to such an embodiment may be referred to as amultiple channel transmitter tag. A smart tag according to an embodimentof the present invention may have information regarding the movement ofthe tag, such as information received from the tag or determined by thetag, for example, using an accelerometer. With movement information, acontroller of a smart tag according to an embodiment of the presentinvention may be able to dynamically adjust (shorter or longer) the timeduration for a frequency hopping burst of location signals. Also, toimprove position determination accuracy, an object tag may blinkmultiple times in succession to provide additional location solutionsand/or to purposefully achieve overdetermination of the position of theobject. Embodiments of the present invention may use a variety oflocation data processing algorithms to determine the position of anobject, such as averaging, median filtering, and Kalman filtering. Anobject tag may also blink periodically so the position of the object maybe monitored over a longer period of time.

In addition to generating a position determination signal comprising aburst of location signals, and potentially embedding a data load in oneor more location signals, an object tag 110 may actively manage themultiple frequency channels used for a burst of location signals, suchas to determine available frequency channels, as identified in block408. For example, an object tag 110 may reduce the number of frequencychannels and location signals transmitted thereon to reduce thepotential interference with other users in those frequency channels.Such a reduction in the number of frequency channels may bepredetermined to define a set of available frequency channels or may beperformed dynamically to exclude one or more frequency channels.Further, for example, an object tag may “listen” to determine if afrequency channel is being used and, if so, temporarily exclude thatfrequency channel from the multiple frequency channels used to transmita burst of a plurality of location signals. This will help to avoidinterference with other transmissions and allows for interoperability.If something is operating in one of the frequency channels, the objecttag can skip the frequency channel during the hop. In an exemplaryembodiment of the present invention, an object tag 110 may include aprocessor or controller that operates in accordance with or similar to acarrier sense multiple access (CSMA) protocols and may advantageouslyoperate with collision avoidance (CA), such as CSMA/CA, to activelymanage frequency channels used for transmitting location signals tominimize coherent interference with other transmissions. A smartcontroller of an object tag of a further embodiment of the presentinvention may even “listen” to determine if any of the frequencychannels are used frequently and should avoid trying to use thefrequency channels for some period of time. This may prevent repeatedlychecking a particular frequency channel only to find out that it isfrequently or continually in use and not available for transmission of alocation signal for a burst of location signals from the object tag. Asa result of managing the multiple frequency channels used for afrequency hopping burst of location signals, an object tag may transmita position determination signals in bursts of location signals overdifferent subsets of multiple frequency channels of a predetermined setof available frequency channels.

If a data load is included (embedded) in one or more location signals ofa position determination signal, as identified in block 406, to minimizethe necessary network throughput, an object tag 110 may minimize sendinga data load, such as to only embed a limited number of instances of thedata load in location signals of the position determination signal, suchas one or twice or some other number of times less than the number oflocation signals. For example, as illustrated in FIG. 8, a data load XYZ824 transmitted in position determination signal 800 may not beretransmitted in each location signal of a position determination signal800, but transmitted only four times throughout the entire frequencyhopping burst of location signals, and only the tag ID 820 (or necessaryportion thereof) and necessary network header 801, 802, 803, 804, 805,806, 807, 808, 809, 810, 811, 812, 813, 814, 815, 816 may be transmittedin each location signal of the position determination signal 800.Further, an object tag 110 operating in accordance with an embodiment ofthe present invention may partition a data load between one or more ofthe location signals of each of two or more position determinationsignals. For example, as illustrated in FIG. 9, a data load may be splitbetween location signals of two position determination signals 900, 930,such two smaller data loads 924 (part 1 of 2) and 926 (part 2 of 2) tocut down on the airtime of location signals carrying the data load.Similarly, a data load may be partitioned and/or repeated between fewerlocation signals of a position determination signal than the number offrequency channels of a predetermined set of available frequencychannels, such as to account for the possibility that one or morefrequency channels may be in use and less than all of the frequencychannels may be included in a burst of location signals, therebyensuring that the entire data load may still be transmitted even if allthe frequency channels are not used. If sixteen frequency channels areavailable, a data load may be partitioned and/or repeated between 2 to15 location signals, such as 12 location signals, or, more generally,between 2 to N−1 location signals where N is the number of possibleavailable frequency channels. For example, FIG. 10 illustrates anembodiment where a data load is split into 6 parts 1031, 1032, 1033,1034, 1035, 1036, and each part is repeated twice over a total of 12location signals of a position determination signal 1000. Even further,an object tag 110 may attempt to balance the data load by partitioning(dividing) and evenly distributing the data between location signalstransmitted over multiple frequency channels. This approach can minimizethe airtime of location signals on each of the involved multiplefrequency channels. Also, particularly if a data load is included, areceiver may send an acknowledgment (ACK) of the confirmed receipt to alocation signal or data load of a position determination signal, such asidentified in block 423. A receiver may validate a location signal, forexample, based upon a tag ID and a cyclic redundancy check (CRC). Tominimize necessary network throughput, acknowledgment of a locationsignal may be sent only when a data load, or a partition thereof, isdetected in a location signal or a burst of location signals for aposition determination signal.

Referring again to the schematic block diagram of FIG. 1 and thefunctional block diagram of FIG. 4, the object tag 110 blinks totransmit a burst of location signals over multiple frequency channels,as identified in block 410, such as in a consecutive or non-consecutivesequence of multiple frequency channels of a predetermined set ofavailable frequency channels. Receivers 1 through n 101, 102, 103, 104,if within range of the transmission of the location signals from theobject tag 110 and within line-of-sight or otherwise without wirelesstransmission obstructions, should receive the location signalstransmitted over multiple frequency channels, as identified in block412. Because of differences in the receivers 1 through n 101, 102, 103,104, such as positions, lines-of-sight, and interference, each ofreceivers may not receive all of the transmitted location signals ofposition determination signal. The location signals that are received byeach of the receivers 1 through n 101, 102, 103, 104 may be used forposition determination as described further herein. Depending upon thetype(s) of location algorithms used for position determination by anembodiment of the present invention (e.g., AoA, ToA, DToA, RSSI, etc.),the receivers may record or determine additional information used by thereceiver or a central computer as location data. For example, a receivermay include a timer, which may also be a clock, and measure arrival timeof location signals, as identified in block 414. A receiver may thenassociate each of the plurality of location signals with thecorresponding arrival time of each respective one of the plurality oflocation signals.

Receivers 1 through n 101, 102, 103, 104 transmit the location signalsand/or location data (e.g., arrival times) of a position determinationsignal to a central processing location, as identified in block 424,such as to processor or controller 122 of central computer 120, whereposition determination can be performed from data received by thecentral computer 120 from multiple receivers 1 through n 101, 102, 103,104, as identified in block 434. Receivers 1 through n 101, 102, 103,104 may be directly connected to central computer 120, such as by wiredor wireless communications between the receivers 1 through n 101, 102,103, 104 and central computer 120. For example, central computer 120 mayinclude a wireless transceiver or interface 126 to receive datatransmissions from wireless transmitters of receivers 1 through n 101,102, 103, 104. Also, a bus 123 may be used to directly couple receiversto central computer 120. Alternatively, receivers 1 through n 101, 102,103, 104 may be indirectly connected to central computer 120, such asthrough a network 130 and a network interface or communication interface124 of central computer 120. Further, receivers 1 through n 101, 102,103, 104 may be indirectly connected to central computer at 120, such asthrough network communications between receivers 1 through n 101, 102,103, 104, illustrated, for example, in FIG. 1 as a serial connectionbetween receiver 1 101 and receiver 2 102. Alternate embodiments of thepresent invention may use one or more of a variety of networkcommunication architectures, such as direct, serial, parallel, mesh, andtree network communication architectures, to communicate betweenreceivers and/or between receivers and a central processing location, aswell as using one or more multi-component architectures, such asemploying one or more bus architectures. Although a central processinglocation is illustrated in FIG. 1 by central computer 120 as a separateentity from any one of the receivers, alternate embodiments of thepresent invention may include all or part of the hardware performed bycentral computer 120 at one or more of the receivers and have a singlecentral processing location or a co-hosted central processing location.

Receivers 1 through n 101, 102, 103, 104 may perform additionalfunctions, as illustrated in FIG. 4. For example, a receiver maydetermine set of time differences of arrival (TDoA) between locationsignals, as identified in block 416. If time differences of arrival aredetermined by a receiver, the receiver does not need to transmit each ofthe arrival times for the location signals to the central processinglocation, but need only transmit the time of arrival of at least one ofthe plurality of location signals and the time differences of arrivalbetween either the one location signal for which the arrival time istransmitted and each of the other plurality of location signals or aserial sequence including each of the plurality of location signalsincluding the one location signal for which the arrival time istransmitted. For example, if there are 4 location signals A, B, C, andD, the TDoA of those signals could be represented by the ToA of A andthe set of time differences of arrival between {AB, AC, AD} orrepresented by the ToA of A and the set of time differences of arrivalbetween {AB, BC, CD}. Either set of data will permit calculation of ToAdata for all 4 of the location signals. Performing such processing at areceiver can de-centralize the processing for position determination anddecrease the processing load on the centralized processing location, andpotentially reduce network communication traffic. Whether measuringarrival times of location signals, determining time differences ofarrival between location signals, or performing another location-basedfunction, a receiver will determine some location data for the pluralityof location signals, as illustrated at block 420, which can betransmitted to and used by a central processing location for positiondetermination. A receiver may also filter or discard unreliable locationsignals, as identified in block 418, or unreliable positiondetermination signals. For example, if a receiver cannot validate alocation signal, the receiver may discard the location signal. If areceiver determines that data for a location signal is outside of anacceptable range of values, the receiver may discard the locationsignal, such as if the time of flight is twice as long as expected, thelocation signal may be discarded as a potential reflection. A receivermay determine an acceptable range of values for location signals basedupon a plurality of location signals received by the receiver. Forexample, if a receiver receives a burst of sixteen location signals, thereceiver may average the signal strengths for all the sixteen locationsignals, and if one of the location signals has a signal strength thatis more than a predetermined range (e.g., 5%, a predetermined value ormagnitude, or any other function) above or below the average signalstrength for all of the sixteen location signals, the receiver maydiscard the outlier location signal. Various additional or alternateselections and filtering may be accomplished based upon any number ofcharacteristics of the received location signals and according to anynumber of corresponding functions, including filtering or discarding anyavailable location signals for an unreliable position determinationsignal. Also, if a data load, or partition thereof, is included in oneor more of the location signals, a receiver may determine (extract) thedata load from the one or more location signals, as identified in block422. If the data load is partitioned between location signalstransmitted over multiple frequency channels for a positiondetermination signal, a receiver may compile the data load partitions.

As described above, receivers 1 through n 101, 102, 103, 104 transmitthe location signals and/or location data (e.g., arrival times) ofposition determination signals to a central processing location, asidentified in block 424, such as to processor or controller 122 ofcentral computer 120, where position determination can be performed fromdata received by the central computer 120 from multiple receivers 1through n 101, 102, 103, 104, as identified in block 434. The centralcomputer 120 receives the location signals and/or location data, andpossibly also a data load if embedded in the location signals of one ormore position determination signals, from the receivers 1 through n 101,102, 103, 104, as identified in block 425. Like receivers 1 through n101, 102, 103, 104, the central computer 120 may also filter or discardunreliable location signals, as identified in block 426, or unreliableposition determination signals. For example, if a location signal ordata for a location signal is not transmitted from at least three of theplurality of receivers, the central computer 120 may weight that signaldifferently or discard that location signal or its correspondingposition determination signal altogether. If the central computer 120determines that data for a location signal is outside of an acceptablerange of values, the central computer 120 may discard the locationsignal, such as if the time of flight is twice as long as expected, thelocation signal may be discarded as a potential reflection. The centralcomputer 120 may determine an acceptable range of values for locationsignals based upon a plurality of location signals or data for aplurality of location signals received from the receivers. For example,the central computer 120 may average the signal strengths for all thelocation signals from one or more of the receivers, and if one of thelocation signals has a signal strength that is more than a predeterminedrange (e.g., 3%, a predetermined value or magnitude, or any otherfunction) above or below the average signal strength, the centralcomputer 120 may discard the outlier location signal. Various additionalor alternate selections and filtering may be accomplished based upon anynumber of characteristics of the received location signals and accordingto any number of corresponding functions, including filtering ordiscarding any available location signals for an unreliable positiondetermination signal. Also, if a data load, or partition thereof, isincluded in one or more of the location signals of a positiondetermination signal, the central computer 120 may determine (extract)the data load from the one or more location signals of the positiondetermination signal, as identified in block 432. If the data load ispartitioned between location signals transmitted over multiple frequencychannels of a position determination signal, as described above, thecentral computer 120 may compile the data load partitions. If the dataload is partitioned between location signals of at least two positiondetermination signals, as described above, the central computer 120 maycompile the data load partitions from the position determinationsignals.

The central computer 120 determines the position of the object, asillustrated at block 434. To determine the position of the object, thecentral computer 120 may determine location data from location signalsand/or location data of one or more position determination signals, asidentified in block 430. For example, less than all the receivers maydetermine location data for the plurality of location signals receivedby that receiver, as illustrated at block 420. As a result, the centralcomputer 120 may need to determine location data from location signals,similar to methods employed by the receivers to determine location datafrom location signals. Further, the central computer 120 may determineadditional location data from preliminary location data determined by areceiver at block 420. Further, to determine the position of the object,the central computer at 120 may correlate data from receivers forfrequency channels for one or more location signals, as illustrated atblock 428. For example, location data from at least two of the receiversfor at least one of the location signals transmitted over one of thefrequency channels may be correlated. Correlating data from multiplereceivers for one or more frequency channels for one or more locationsignals refers to the underlying computations for the variousmethodologies for real-time locating position determination, such ascomputing the distance between each receiver and the object and thencomputing the possible intersection of the distances to determine theposition of the object. To correlate data from multiple receivers, thecentral computer at 120 typically will already have available the fixedposition data for each receiver. In addition, various known and futuredeveloped position determination functions and improvements may also beapplied by embodiments of the present invention, such as correcting forclock drift between receivers. Further, embodiment of the presentinvention may rely upon more than one location methodology, such as ToAand RSSI or DToA and RSSI.

FIG. 4 also illustrates the functions of blocks 404, 406, 408, and 410as a collection 400. This illustration refers to an embodiment of thepresent invention where each of the functions of blocks 404, 406, 408,and 410 are performed by an object tag. Function blocks 412, 414, 416,418, 420, 422, 423, and 424 are illustrated as a collection of 401referring to an embodiment of the present invention where each of thefunctions are performed by receivers. Function blocks 425, 426, 428,430, 432, and 434 are illustrated as a collection of 402 referring to anembodiment of the present invention where the functions are performed bya central computer. However, the functions identified in each ofcollections 400, 401, 402 are not exclusive for all embodiments of thepresent invention. For example, function blocks 416, 418, 420, and/or422 may be performed by a central computer, rather than receivers.

FIG. 5 illustrates a block diagram of a wireless tag according to atleast one embodiment of the present invention. A wireless tag 220 may beattached to or included (embedded) as part of an object 200. Typically,wireless tag 220 will include a power source 230. Alternate embodimentsof the present invention may use a transponder, in addition to or ratherthan a transceiver 226 or transmitter 225 that requires a power source230. As such, wireless tag 220 may be either a passive tag or an activetag. The wireless tag 220 may also include a processor or controller222, a wireless transceiver 226, and memory 228. The wirelesstransceiver 226 may include a transmitter 225 and a receiver 227.Alternate embodiments of the present invention may instead use separatetransmitter 225 and receiver 227, or only a transmitter 225. The memory228 may store data for the wireless tag 220, such as the tag ID, and mayor may not be writable or updateable.

FIG. 6A illustrates a block diagram of a single channel receiver (SCR)according to one embodiment of the present invention. Receiver 600 mayinclude a wireless interface 606 to receive location signals forinterpretation by subreceiver 608. Subreceiver 608 may be designed tomonitor the first channel for the beginning of a burst sequence oflocation signals of a position determination signal. Upon finding avalid location signal on the first channel, subreceiver 608 may sequencein accordance with a burst channel order. Subreceiver 608 may, forexample, measure tag signal RSSI and, using the timer 604, ToA.Subreceiver 608 may also include a processor or controller 602 that maydirect operation of the subreceiver 608 and perform additionalfunctionality, such as validating a location signal, calculating timedifference of arrival, and extracting and compiling a data load. Asingle channel receiver may be a simple construction using a single ASICand may have a low cost, but has a corresponding low tag-trackingcapacity, and location signal receipt fails if detection on themonitoring channel fails. Embodiments of the present invention employingsingle channel receivers may benefit from multiple tag bursts (blinks)to increase the chance that single channel receivers will detect alocation signal on the monitoring channel. Receiver 600 may also includeat least one communication interface 642, such as to communicate with acentral computer via communication interface 342.

FIG. 6B illustrates a block diagram of a multiple channel receiver (MCR)according to one embodiment of the present invention. The receiver 620may include a wireless interface with a radio frequency divider 626 todivide the received location signals of a position determination signalfor interpretation by subreceivers that each individually monitor asubset of possible frequency channels for the location signals. Forexample, subreceivers A, B, C, and D 630, 632, 634, 636 may be includedthat each sequence through 4 of 16 frequency channels. Each subreceivermay be a separate ASIC, have a monitoring channel, such as the firstchannel in the sequence for its subset of frequency channels, and willsequence through the subset of frequency channels if a location signalis detected on its monitoring channel. A multiple channel receiver mayhave a higher cost due to use of multiple ASICs, but will have acorresponding higher tag-tracking capacity and fewer failures. Even if alocation signal receipt fails on a monitoring channel of one ASIC, theother ASICs may still receive location signals. The receiver 620 mayalso include a controller 622 and a timer 624. The timer 624 may be usedby all of the subreceivers A, B, C, and D 630, 632, 634, 636 and/or bythe controller for time of arrival measurements and, if performed,differential time of arrival computations. The controller 622 mayperform additional functionality, such as validating a location signal,calculating time difference of arrival, and extracting and compiling adata load. Alternate embodiments of multiple channel receivers accordingto the present invention may be constructed to monitor C channels usingN channels per subreceiver. For example, the illustrated embodimentincludes four subreceiver ASICs. An alternate embodiment for the 2.4 GHzband may include 16 subreceiver ASICs, one for each channel, or 8subreceiver ASICs, one for each two channels. Receiver 620 may alsoinclude at least one communication interface 643, such as to communicatewith a central computer via communication interface 342.

FIG. 6C illustrates a block diagram of a wideband receiver (WBR)according to one embodiment of the present invention. Receiver 680 mayinclude a wireless interface 686 to receive location signals forinterpretation by the subreceiver 688. Subreceiver 688 may be designedto simultaneously monitor all channels of interest, such as all channelsof a predetermined set of available frequency channels for locationsignals. Subreceiver 688 may also include a processor or controller 682that may direct operation of the subreceiver 688 and perform additionalfunctionality, such as validating a location signal, calculating timedifference of arrival, and extracting and compiling a data load. Awideband receiver will have a high tag-tracking capacity and also willhave a high reliability for location signal capture. Receiver 680 mayalso include at least one communication interface 644, such as tocommunicate with a central computer via communication interface 342.

FIG. 7 illustrates a block diagram of a computer that may be used tofacilitate position determination based upon frequency channel diversityaccording to at least one embodiment of the present invention. Thecomputer of FIG. 7 may be capable of and configured to operate as acentral processing location and central computer 120 in accordance withembodiments of the present invention. Although shown as separateentities, in some embodiments, one or more entities may support one ormore logically separated but co-located entity. For example, a singleentity may support a logically separate, but co-located, receiver andcentral computer, such as receiver 2 102 and the central computer 120.The computer of FIG. 7 includes various means for performing one or morefunctions in accordance with exemplary embodiments of the presentinvention, including those more particularly shown and described herein.It should be understood, however, that one or more of the entities mayinclude alternative means for performing one or more like functions,without departing from the spirit and scope of the present invention.More particularly, for example, as shown in FIG. 7, the computer caninclude a processor, controller, or like processing element 328connected to a memory 326. The memory may comprise volatile memory 314and/or non-volatile memory 318. Memory 326 may be, for example, readonly memory (ROM), random access memory (RAM), a flash drive, a harddrive, and/or other fixed or removable data memory or storage device.Memory 326 typically stores content, data or the like. For example, thememory typically stores content transmitted from and/or received by thecomputer. Also for example, the memory is a non-transitorycomputer-usable storage medium and stores computer program code orcontrol logic, such as for effectuating operating systems and positiondetermination, for the processor to perform steps associated withoperation of the computer in accordance with embodiments of the presentinvention.

The processor 328 may also be connected to a position determinationmodule 330. The position determination module 330 may be software and/orsoftware-hardware components. For example, a position determinationmodule 330 may include software and/or software-hardware componentscapable of performing computations on the available location signals,location data, and/or other data to determine the position of an object.The position determination module 330 may additionally or alternativelyinclude firmware. Generally, then, the position determination module 330can include one or more logic elements for performing various functionsof position determination. As will be appreciated, the logic elementscan be embodied in any of a number of different manners. In this regard,for example, the logic elements performing the functions of one or moreclient applications can be embodied in an integrated circuit assembly.

The processor 328 can also be connected to at least one interface orother means for displaying, transmitting and/or receiving data, content,or the like. In this regard, the interface(s) can include at least onecommunication interface 342 or other means for transmitting and/orreceiving data, content, or the like. When the computer provideswireless communication to operate in a wireless network, the processor328 may operate with a wireless communication subsystem 312 of thecommunication interface 342. More particularly, for example, thewireless communication subsystem 312 may include output 344 and input346. The communication interface 342 can include a radio frequency (RF)transceiver or interrogator 360 so that data can be shared with and/orobtained from electronic devices in accordance with RF techniques. Thecomputer can additionally, or alternatively, include other transceivers,such as, for example an infrared (IR) transceiver 362 and/or a Bluetooth(BT) transceiver 364 operating using Bluetooth wireless technologystandardized by the Bluetooth Special Interest Group. The computer cantherefore additionally or alternatively be configured for transmittingdata to and/or receiving data from electronic devices in accordance withsuch techniques. The computer can additionally or alternatively beconfigured for transmitting and/or receiving data from electronicdevices according to a number of different wireless networkingtechniques, including WLAN, WiMAX, UWB, IEEE802.15.4a, ZigBee, or thelike. The communication interface 342 may also include an IEEE 1394interface 368 and a network interface 370.

In addition to the communication interface 342, the interface(s) canalso include at least one user interface that can include a user inputinterface 332 and a user output interface 334. The user input interface332 can comprise any of a number of devices allowing the computer toreceive data from a user, such as a microphone, a keyboard or keypad333, a mouse or pointer 335, a touch display, a joystick, or other inputdevice. The user output interface 334 can comprise any of a number ofdevices allowing the computer to provide data to a user, such as adisplay 337, a speaker 338, and a printer. One or more processors,memory, storage devices, and other computer elements may be used incommon by a computer system and subsystems, as part of the sameplatform, or processors may be distributed between a computer system andsubsystems, as parts of multiple platforms, such as a co-hosted centralprocessing location of an embodiment of a frequency channel diversityreal-time locating system.

According to one aspect of the present invention, the functionsperformed by one or more of the entities of the system, such as tag 110,receivers 1 through n 101, 102, 103, 104, central computer 120, wirelesstag 220, single channel receiver 600, multiple channel receiver 620,wideband receiver 680 and the computer of FIG. 7, may be performed byvarious means. In addition, FIG. 4 illustrates a functional blockdiagram or flowchart of frequency channel diversity location positiondetermination according to at least one embodiment of the presentinvention. The functions of the flowchart may be embodied in systems,methods, and computer program products according to exemplaryembodiments of the invention. In this regard, each block or operation ofthe functional block diagram or flowchart, and combinations of blocks inthe functional block diagram or flowchart, can be implemented by variousmeans. Means for performing functions by one or more entities of thesystem and/or for implementing the blocks or operations of theflowcharts, and/or combinations of the blocks or operations in theflowchart, may include hardware and/or a computer program productincluding one or more computer program code instructions, programinstructions, or executable computer-readable program code instructions.In one exemplary embodiment, one or more of the procedures describedherein may be embodied by a computer program product including programcode instructions may be stored by memory 326 and executed by aprocessor 328. As will be appreciated, any such computer program codeinstructions may be loaded onto a computer or other programmableapparatus (i.e., processor and/or memory hardware) to produce a machine,such that the instructions which execute on the computer or otherprogrammable apparatus create means for implementing the functionsspecified in the functional block diagram and flowchart block(s) oroperation(s). A computer program product for performing one or morefunctions of embodiments of the present invention includes anon-transitory computer-usable storage medium (also a computer-readablestorage medium), such as a non-volatile storage medium, and softwareincluding computer-readable program code portions or control logic, suchas a series of computer instructions, embodied in and stored on or bythe computer-usable storage medium, and that can direct a computer, aprocessor, or other programmable apparatus to function in a particularmanner, such that the instructions stored in the computer-usable storagemedium produce an article of manufacture including instruction meanswhich implement the function specified in the functional block diagram'sand flowchart's block(s) or operation(s). The computer program codeinstructions may also be loaded onto a computer, processor, or otherprogrammable apparatus to cause a series of operations to be performedon or by the computer, processor, or other programmable apparatus toproduce a computer-implemented process such that the instructions whichexecute on the computer, processor, or other programmable apparatusimplement the functions specified in the functional block diagram's andflowchart's block(s) or operation(s). Similarly, embodiments of thepresent invention may be incorporated into hardware and software systemsand subsystems, combinations of hardware systems and subsystems andsoftware systems and subsystems, and incorporated into network devicesand systems. In each of these network devices and systems, as well asother devices and systems capable of using a system or performing amethod of the present invention as described above, the network devicesand systems generally may include a computer system including one ormore processors that are capable of operating under software control toprovide the techniques described above.

Accordingly, blocks or operations of the functional block diagrams andflowchart support combinations of means for performing the specifiedfunctions, combinations of operations for performing the specifiedfunctions and program instruction means for performing the specifiedfunctions. It will also be understood that one or more blocks oroperations of the functional block diagram and flowchart, andcombinations of blocks or operations in the functional block diagram andflowchart, can be implemented by special purpose hardware-based computersystems and/or processors which perform the specified functions oroperations, or combinations of special purpose hardware and computerprogram code instructions.

Provided herein are improved architectures, systems, methods, andcomputer program products for real-time object locating and positiondetermination using frequency channel diversity for transmitting andreceiving position determination signals including bursts of locationsignals. Channelized frequency diversity of a short burst of smalllocation signals that “hop” across multiple frequency channels is usedto collectively produce a quasi-wideband position determination signal.Object tags operating with frequency channel diversity for transmittinglocation signals of position determination signals require low powerconsumption, but can still efficiently provide adequate positiondetermination signal for reliable position determination.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.moreover, although the foregoing descriptions and the associateddrawings described exemplary embodiments in the context of certainexemplary combinations of elements and/or functions, it should beappreciated that different combinations of elements and/or functions maybe provided by alternative environments without departing from the scopeof the appended claims. In this regard, for example, differentcombinations of elements and/or functions other than those explicitlydescribed above are also contemplated as may be set forth in some of theappended claims. Although specific terms are employed herein, they areused in a generic and descriptive sense only and not for purposes oflimitation.

That which is claimed:
 1. A method comprising: receiving, from at leastone receiver configured to detect a location signal according to a firstsignal polarity, a first instance of the location signal; receiving,from at least one receiver configured to detect the location signalaccording to a second signal polarity different than the first signalpolarity, a second instance of the location signal; determining, by aprocessor, a position of an object based on at least one of the firstinstance of the location signal and the second instance of the locationsignal, wherein the location signal is transmitted from at least one tagconfigured to transmit the location signal according to the first signalpolarity and the second signal polarity.
 2. A method as defined in claim1, wherein the at least one receiver configured to detect the locationsignal according to the first signal polarity is configured to monitor afirst frequency channel and a second frequency channel different thanthe first frequency channel.
 3. A method as defined in claim 2, whereinthe at least one receiver configured to detect the location signalaccording to the second signal polarity is configured to monitor thefirst frequency channel and the second frequency channel.
 4. A method asdefined in claim 1, wherein the at least one receiver configured todetect the location signal according to the first signal polarity isconfigured to monitor a first set of frequency channels and a second setof frequency channels different than the first set of frequencychannels.
 5. A method as defined in claim 1, wherein a first one of theat least one tag is configured to transmit the location signal accordingto the first signal polarity, and a second one of the at least one tagis configured to transmit the location signal according to the secondsignal polarity.
 6. A method as defined in claim 1, wherein a controllerof the at least one tag is configured to dynamically adjust a timeduration of a burst of the location signal.
 7. A method as defined inclaim 1, wherein a controller of the at least one receiver is configuredto discard the location signal in response to the location signal beingoutside of an acceptable range of values.
 8. A method as defined inclaim 1, further comprising measuring a first arrival time of the firstinstance of the location signal and a second arrival time of the secondinstance of the location signal, wherein the determining of the positionof the object is based on the first and second arrival times.
 9. Amethod as defined in claim 1, wherein the at least one receiverconfigured to detect the location signal according to the first signalpolarity is a same receiver as the at least one receiver configured todetect the location signal according to the second signal polarity. 10.A system as defined in claim 1, wherein the first receiver is a samereceiver as the second receiver.
 11. A system comprising: a firstreceiver configured to receive a location signal transmitted at a firstsignal polarity; a second wireless receiver configured to receive thelocation signal transmitted at a second signal polarity, wherein thefirst signal polarity is at a different polarity than the second signalpolarity; a controller configured to determine a position of an objectbased on the location signal as received at the first wireless receiverand as received at the second wireless receiver.
 12. A system as definedin claim 11, wherein the first receiver is configured to monitor a firstfrequency channel and a second frequency channel different than thefirst frequency channel.
 13. A system as defined in claim 12, whereinthe second receiver is configured to monitor the first frequency channeland the second frequency channel.
 14. A system as defined in claim 11,wherein the first receiver is configured to monitor a first set offrequency channels and a second set of frequency channels different thanthe first set of frequency channels.
 15. A system as defined in claim11, further comprising tags configured to transmit the location signalaccording to the first signal polarity and the second signal polarity.16. A system as defined in claim 11, wherein the tags are configured todynamically adjust a time duration of a burst of the location signal.17. A system as defined in claim 11, wherein the controller isconfigured to discard the location signal in response to the locationsignal being outside of an acceptable range of values.
 18. A system asdefined in claim 11, wherein the controller is configured to measure afirst arrival time of a first instance of the location signal and asecond arrival time of a second instance of the location signal, and thedetermination of the position of the object is based on the first andsecond arrival times.